VS Code Extensions
Blue Matter for VS Code

Blue Matter for VS Code

by blue-matter

Blue Matter is a VS Code extension that explains selected code in plain English using AI, repository context, Jupyter notebook context, workspace indexing, caching, and CodeLens.

Downloads

17

Rating

5.0 / 5 (1)

Version

0.1.0

Last updated

Apr 04, 2026

Context-aware AI explanations for any code you select. Understands your repo, caches results, and explains in plain English.

Setup (3 steps)

  1. Install the Blue Matter extension from the VS Code Marketplace.
  2. Get a free API key at openrouter.ai/keys.
  3. Run Blue Matter: Set API Key from the Command Palette (Cmd+Shift+P).

Features

  • Explain Selected Code — Select any code block and press Cmd+Shift+E (Mac) / Ctrl+Shift+E (Windows/Linux). An explanation appears in a side panel instantly.
  • Inline CodeLens — "Explain" button appears above your selection. Click to explain without using the keyboard shortcut.
  • Jupyter notebook support — Works inside .ipynb notebook cells. Blue Matter automatically includes context from earlier cells (imports, variables, functions) so explanations reference what was defined previously.
  • Python cell mode — Works in .py files that use # %% cell markers (VS Code Python Interactive Window / Jupyter-style cells).
  • From cache — Previously explained code loads instantly from a local cache with no API call.
  • Annotations — Add your own notes to code blocks with Cmd+Shift+N. Search them later with Blue Matter: Search Annotations.
  • Workspace indexing — Blue Matter indexes your repo's symbols and imports (including .ipynb notebooks) to give richer, context-aware explanations.

Keyboard Shortcuts

Command Mac Windows / Linux
Explain Selected Code Cmd+Shift+E Ctrl+Shift+E
Add Annotation Cmd+Shift+N Ctrl+Shift+N

Privacy

In standard mode, selected code is sent to OpenRouter's API for AI processing. OpenRouter's privacy policy applies.

In strict mode (Settings → Blue Matter: Privacy Mode → strict), all AI calls are disabled — only previously cached explanations are shown. No code ever leaves your machine.

Your API key is stored in your OS keychain via VS Code SecretStorage and is never written to settings files or logs.

Supported Languages

Full context-aware explanations (with repo map):

  • JavaScript / TypeScript (.js, .ts, .jsx, .tsx, .mjs, .cjs)
  • Python (.py, .ipynb)

All other languages work for basic explanation without repo-map context.

Known Limitations (v0.1)

  • Multi-root workspaces: only the first folder is indexed.
  • Symbol extraction uses regex (no full AST); complex patterns may be missed.
  • Rate limit resets on VS Code restart (not persisted to disk).

License

MIT — see LICENSE.